public class Test {
    //static void main(String[] args) {

    //}
    public static void main(String[] args) {
        int n=7;
        int i=2;
        for ( i = 2; i <=Math.sqrt(n) ; i++) {
            if(n%i==0){
                break;

            }
        }
        if(i>Math.sqrt(n)){
            System.out.println(n+"是素数！");
        }
    }
}//单行注释
